Network of single rods welded together at their junctions



4 4 l Rw .u www www 30+, mw m R2 E H T T A mm m Em NT ND Um Hm dal* C MLE. Em m. l.' fm G m l F om M 2K1 am, 1g 9w1 1E.- Il' Nh 1 m 1 a M c d e.w D i F United States 3,067,844 Patented Dec. 11, 1962 f fie Thepresent invention pertains to triangular structural hollow members andto a network of single members welded together at their junctions.

An object of the invention is to provide a triangular structural memberprovided with fillets within its corners.

Another object of the invention is to provide a triangular hollowstructural member having one leg thereof slotted.

Still another object of the invention is to provide a triangularstructural member having llets within its corners, with one leg slotted,and having a prole mass distribution selected for optimum e'ciency,while utilizing a minimum mass necessary.

Another object of the present invention is to provide a networkincluding top members and diagonal members of the triangular hollowprofile of the present invention, having a high structural strength, butrequiring a lesser amount of materials than conventional up to present.

n Another object of my invention is to prevent buckling of the membersin any direction.

A still further object of my invention is to keep the labour expenditurelow as regards both the production of the member profiles and theformation of the junctions.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed .description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the figures thereof andwherein:

vlFIGURE 1 shows by way of example, in elevation a network havingascending and descending diagonal members;

FIGURE 2 illustrates, on an enlarged scale, in elevation, the junctionshown in FIGURE l by the circle A;

. FIGURES 2a and 2b are cross-sectional views of the diagonal membersshown in FIGURE 2;

FIGURE 3 is a cross-sectional view of the top member and the connectionof the tension member of FIG- URE 2 to the top member and the bottommember shown in cross-section;

FIGURE 4 shows the shape of the triangular proiile together with aninsertion in cross-section;

FIGURE 5 shows in cross-section a junction of a spatial network andFIGURES 6 and 7 show other shapes and sections of the triangular prole.

In the construction shown in FIGURE 1, the compression members are shownin thicker lines to differentiate them from the tension member, shown bythinner lines. Whilst the diagonal members subjected to tension haveangular proles and the bottom members have U-proiiles, the members ofthe top member and the diagonal members subjected to compression havehollow triangular profiles., IThe triangular profiles have a peripheryof an equilateral triangle, one lside of which,lis open. All three kindsof members are so arranged in the network (see FIGURES 2 and 3) thattheir axis of symmetry lies in the plane of the network and theiropening lies below. Thus the proles allow the water to run away as inthe case of a roof, and the danger of corrosion is reduced.

In order to connect the diagonal members 2 and 3 to the members 1 of thecompression girder, the opening of the member of the compression girderis closed by anv insertion 4, welded therein. In the present case theinsertion 4 has a T-prole, the web of which projects inwards. Theprofile of the insertion may be of a different shape, or use may be madeof a simple metal sheet.V

This completion of the original triangular profile imparts to it anincreased rigidity and permits connection of the diagonal members toilat surfaces of the membersy of the compression girder and of themembers 5 of the tension girder having a U-proiile. Thus, theincorporation of the diagonal members requires only at sections and thewelding is effected by means of seams 6, 7 running transversely to theaxes of the members. These have the advantage of avoiding thelongitudinal and' transverse seams which may arise without such sectionsand which would provide different elasticity in the same connection.

As can be seen from FIGURE 4, the edges of the triangular prole and ofthe insertion 4 lying opposite each other are so bevelled that grooves 8are formed for V-shaped welding seams. The three corners of the proleare strengthened inwards by the formation of approximately triangularsurfaces in the corners of the profile. In this way the cross sectionalsurface is divided into three different kinds of surfaces, as indicatedby different hatchings. f1 is a surface containing the reinforcement ofthe upper edge, f3 are the two surfaces containing the reinforcement ofthe lower corners, and f2 are the remaining surfaces of the sides of thetriangle. The boundaryY In the prior art, these two requirements couldnot be' satisfied by the same means. As regards the rst requirement, theprofile is the more economical the greater its moment of inertia withrespect to the surface of its cross-section. However, this requirementfor thinness of profile contradicts the requirement for a great wallthickness as a security against torsion.

Experiments were made which show that these two -re-v quirements can befulfilled satisfactorily if use is made of an open triangular profileaccording to the invention,V

Thus,-

the cross-section of which follows a definite rule. it has been foundthat a strengthening of the corners of the prole towards the inside isof special importance; moreover, the surface f1, the two surfaces f2taken together, and the two surfaces f3 taken together have to amounteach to approximately 1/a of the total surface of the prole. An optimumof the bearing strength can be obtained if, over a length ten timestheir thickness the sides of the triangular profile haveparallel'boundary 'sur-A X and Y are the twov 3 faces (FIGURE 6), and ifthe greatest radius of gyration with respect to the axis 9-9 of one ofsurfaces f3 is one quarter of the smallest radius of gyration of thewhole profile. Under this condition, one can obtain a profile value Mini2 of only 1.75, which may be improved to 1.4, if the thickness of thesides is reduced to 1A5' of their length U2 in FIGURE 7) where F is thecross section area of the profile but in rthat case the open triangularprofile must be closed in -the middle of the member, or by means of twometal sheets 10 arranged at 'distances of 1/3 of the profile length. Inthis ease' alsoV the surfaces f1" and f3" are slightly smaller than inFIGURE 6.

The junctionA of the spatial network (FIGURE S), for instance afour-legged grid mast, shows a vertically placed triangular profile 11,which is closed in the region of the junction by a welded-in insertion12, whereby it is ensured against any changev of shape. The stays arewelded on to the surfaces of the triangular rod in the planes 13 and 14.n t

The buckling process of open profiles having a mini mum mass is verycomplicated. The buckling due to the bending of the member axis, aspreviously calculated, is initiated earlier owing to too smallresistance against deformation and torsion of the member. It would bedifficult to ascertain by calculation these influences dependent uponthe shape of .the profile. The rules above indicated with respect to thefor'rn of the cross-section of the triangular member therefore could bedetermined only by a series of tests. Moreover, in the form of thecross-section according to the invention, the moments of inertia relatedto the main axes X and Y are nearly equal to each other, so that oneca'n obtain the full bearing strength with the smallest cross-section,whilst avoiding buckling in any direction.

The amount of labour used is small, since the trianguiar profiles can beobtained bythe usual drawing proc= esses, and since the connection ofthe stays to the chords is simpler, the fiat sections being provided onthe stays, than in the case of sections which are not even, or when thespatial curved sections of tubes are used.

The formation of the junctions may be easily adapted, by the welding-inof more or less thick metal sheets or T-profiles, to the forces arisingin the rods.

It should be understood, of course, that the foregoing disclosurerelates to only preferred embodiments of the invention and that it isintended to cover all changes and modifications of the examples of theinvention herein chosen for the purposes of the disclosure, which do notconstitute departures from the spirit and scope of the invention setforth in the appended claims.

I claim:

l. A compression member for a network of members welded together attheir junctions, of one piece and hollow and of a cross section boundedexteriorly by an equilateral triangle, one triangle side having a slotand the surfaces of the hollow at the corners being concave and moredistant from the external surface than at the middle of two sides, abridging plate at spaced intervals along the length of said slot, andsecured to the edges thereof, the cross section of the compressionmember being divided into ve parts, the cross section part lyingopposite the slot and bounded by parts of the outer triangle sides and atangent to the concave surface of the hollow normal to the axis ofsymmetry, two equal cross section parts each bounded by one of the firstnamed triangle sides, the third triangle side and by the tangent to theconcave surface of the hollow normal to the one of the first namedtriangle sides, two equal parts each lying between the first tangent andone of the second tangents, and wherein the first cross section part andthe sum of the second cross section parts and Athe sum of the last crosssection 4 parts each equals one third of the entire cross sectionalarea.

2. A compression member for a network of members welded together attheir junctions, of one piece and hollow and of a cross section boundedexteriorly by an equilateral triangle, one triangle side having a slotand the surfaces of the hollow at the corners being concave and moredistant from the external surface than at the middle of two sides, abridging plate at spaced intervals along the length of said slot, andsecured to the edges thereof,

:herein the cross section part bounded bythe tangent to the concavesurface of the hollow normal to the axis of symmetry, the two crosssection parts each bounded by a tangent to the concave surface of thehollow normal to one of the closed triangle sides, and the two remainingcross section parts are so related that the last named cross sectionparts have each a length equal to fifteen times their thickness and thelargest radius of gyration of one of the cross section parts adjacentthe slot is about one fourth of the smallest radius of gyration of theentire cross section.

3. A compression member for a network of members welded together'attheir junctions, of one piece and hollow and of a cross side having aslot and the surfaces of the hollow at the corners being concave andmore distant from the external surfaces than at the middle of two sides,a bridging plate at spaced intervals along the length of said slot, andsecured to the edges thereof, the cross section of the compressionmember Ibeing divided into five parts, the cross section part lyingopposite the -slot and bounded by parts of the outer triangle sides anda tangent to the concave surface of the hollow normal to the axis ofsymmetry, two equal cross section parts each bounded by one of the firstnamed triangle sides, theY third triangle side and by the tangent to theconcave surface of the hollow normal to the one of the first namedtriangle sides, two equal parts each lying between the first tangent andone of the second tangents, and wherein the first cross section part andthe sum of the second cross section parts and the sum of the last crosssection parts each equals one third of the entire cross sectional areaand wherein the cross section part bounded by the tangent to the concavesurface of the hollow normal to the axis of symmetry, the two crosssection parts each bounded by a tangent to the concave surface of thehollow normal to one of the closed triangle sides, and the two remainingcross section parts are so related that the last named cross sectionparts have each a length equal to fifteen times their thickness and thelargest radius of gyration of one of the cross section parts adjacentthe slot is about one fourth of the smallest radius of gyration of theentire cross section.

4. A compression member for a network of members welded together attheir junctions, of one piece and hollow and of a cross section boundedexteriorly by an equilateral triangle, one triangle having a slot andthe sur- `faces of the hollow at the corners being concave and moredistant from the external surfaces than at the middle of two sides, abridging plate at spaced intervals along the length of said slot, andsecured to the edges thereof, the cross section of the compressionmember being divided into live parts, the cross section part lyingopposite the slot and bounded by parts of the outer triangle sides and atangent to the concave surface of the hollow normal to the axis ofsymmetry, two equal cross section parts each bounded by one of the firstnamed triangle sides, the third triangle side and by the tangent to theconcave surface of the hollow normal to the one of the first namedtriangle sides, two equal parts each lying between the first tangent andone of the second tangents, and wherein the first cross section and thesum of the second cross section parts and the sum of the last crosssection parts each equals one third of the entire cross sectional area,and wherein the cross section part bounded by the tangent to the concavesurface of the hollow normal to the axis of symmetry, the two crosssection parts each bounded by a tangent to the concave surface of thehollow normal to one of the closed triangle sides, and the two remainingcross section parts are so related that the last named cross sectionparts have each a length equal to fifteen times their thickness and thelargest radius of gyration of one of the cross section parts adjacentthe slot is about one fourth of Ithe smallest radius of gyration of theentire cross section, the slot being bridged by a plate closing thepartly open triangle side in the middle of the compression memberlength.

References Cited in the le of this patent UNITED STATES PATENTS LachmanNov. 23, lPratt Apr. 25, Butz Sept. 9, Butz Sept. 9, Klemperer Mar. 19,Toussaint Dec. 1,

FOREIGN PATENTS France Jan. 6, Italy Nov. 25,

